Modding a MF X-LPS...

I'll do the usual diode upgrade, increase the capacitance on the PSU
section, link out the O/P DC blocking caps (but will probably have to
keep the I/P DC blockers) and probably refresh the remaining
electro-caps. I will also use a more capable linear PSU.

Unfortunately I
have not found a circuit diagram for it.

The only point I'm stuck on is the op-amps. They are marked SSM f
69PH. I've found a few other folk asking about these but no answers and hence don't know if the pin out is standard. Is
it something anyone has come across before? I'm just wondering if it was OK to drop in a more modernreplacement e.g. AD797 .

Comments

Board now stripped down of all the cheap and nasty stuff MF threw in (as far as necessary) and ready for some decent new parts. I found it had a basic voltage doubler on board so have removed the section permanently and intend to make a proper 12-0-12 regulated supply for it.A little bit of reverse tracking the board showed the opamps were not of standard pinout so they'll be staying. On the plus side a friend was familiar with a sister model and knew it to be of good quality and very low noise.

There will be a fair pause before the next installment as I'm very lazily putting a parts order together for this and a few other mini-projects.

All cheap 'n' nasty electro-caps were replaced with better quality ones from ranges more appropriate to the job being done (signal or power). I also uprated the power line caps from 16v to 25v. I've done this as I intend to increase the power supply from 12v (doubled) to a proper 15-0-15 linear supply. That is the reason for the power regulation area of the board being mainly left blank. This supply will be fed in where the regulators used to be.

The cheapy film caps have also been replaced, polyester for power and polypropylene for signal which are also of better tolerance.

I have added heat sinks to the dual transistors as a "just-in-case" measure with the voltage increase in mind. Heat sinks also added to the op-amps, this is from previous experience of using "metal can" versions of op-amps that give slightly improved performance which has been put down to the better heat dissapation of the metal can body. As the op-amps here are of unknown spec. there is no chance of finding a metal can alternative so hopefully the heat sinks will achieve some tiny advantage.Just for hell of it I changed the diffused red LED for a more modern clear purple one.

Power supply built, 30va 15-0-15 toroid, regulated psu and a ripple rejection board. Hopefully putting out a vastly superior +15/0/-15 directly into the power rails of the X-LPS.Power and signal cables uprated as well.Now on soak test and run in (the larger caps in the ripple rejection board take 24-48 hours to fully form and settle down) before any listening takes place.

I had my first little (meant to be) listen last night to my modded X-LPS. My deck is not the best i.e. Manticore Mantra, Rega RB300 and, erm, name of cartridge escapes me for now but a step or two above a basic MM.

When I first tried the standard X-LPS it was quite decent but did lack authority and tunefulness in the bass registers especially and the sound stage was rather flat. In comparison to the e.g. built in phono of the Claymore there was a mixed bag of differences. The Claymore stage has more bass and better sound stage compared to the X-LPS's better mid and high end detail and generally carrying the tune better.

Post mods I was hoping for a general, slightly more than subtle improvement across the board. What I actually heard was like a totally different phono stage. From the first few bars of music it was obvious the sonic differences were radical.The bass was positively astounding in it's extra depth and clarity, acoustic instruments and voices were really shining out with far more realistic tone & timbre and little deatails I hadn't heard since my previous, much better turntable setup, were coming through very clearly. The HF's also took on a much sweeter tone but with more clarity also. It now presents quite a decent sound stage in both depth and width.

Overall I'm pretty gob-smacked by the improvement being so across the board and extreme. Very pleased indeed to the extent of thinking on a better cartridge, oh dear, the rot starts!

It's impossible to say for sure where to attribute how much of the improvement to, between the PSU upgrade and the on-board tweaks. At a guess I'd say the bass and tone are due mainly to the PSU with detail and sound staging being more to the component changes.

I'll dub it the "Xtra-LPS" or maybe the "Super Carlos Fandango Purple Pileus"

I had my first little (meant to be) listen last night to my modded X-LPS. My deck is not the best i.e. Manticore Mantra, Rega RB300 and, erm, name of cartridge escapes me for now but a step or two above a basic MM.

When I first tried the standard X-LPS it was quite decent but did lack authority and tunefulness in the bass registers especially and the sound stage was rather flat. In comparison to the e.g. built in phono of the Claymore there was a mixed bag of differences. The Claymore stage has more bass and better sound stage compared to the X-LPS's better mid and high end detail and generally carrying the tune better.

Post mods I was hoping for a general, slightly more than subtle improvement across the board. What I actually heard was like a totally different phono stage. From the first few bars of music it was obvious the sonic differences were radical.The bass was positively astounding in it's extra depth and clarity, acoustic instruments and voices were really shining out with far more realistic tone & timbre and little deatails I hadn't heard since my previous, much better turntable setup, were coming through very clearly. The HF's also took on a much sweeter tone but with more clarity also. It now presents quite a decent sound stage in both depth and width.

Overall I'm pretty gob-smacked by the improvement being so across the board and extreme. Very pleased indeed to the extent of thinking on a better cartridge, oh dear, the rot starts!

It's impossible to say for sure where to attribute how much of the improvement to, between the PSU upgrade and the on-board tweaks. At a guess I'd say the bass and tone are due mainly to the PSU with detail and sound staging being more to the component changes.

I'll dub it the "Xtra-LPS" or maybe the "Super Carlos Fandango Purple Pileus"

:-c

Thanks for this CJ.It's really catching my imagination this project.The idea that one can upgrade one's system component-by-component is blowing my mind! @-)I understand that without a labourious testing process it's impossible to know which component change is affecting which sonic change, but what's your hunch as to which components are most worth considering for upgrade?

I would not claim to possess enough understanding of electronics to give an answer of any merit. However, from past experience and following the lead of people with more knowledge than me, the power supply area is the place to start and reaps the greatest improvements. What you actually change depends entirely on what the manufacturer originally fitted. Some being better than others. If the psu is built in and a linear type then uprating the rectifier diodes to ultra fast and possibly greater current if you also increase the capacitance of the main tank capacitors is usually very beneficial. I'm not a great believer in boutique parts but have used them on the odd occasion to obtain far more subtle improvements. It's more important to be sure the components are appropriate to the job they are doing, like I stated in my first description. If the item is particularly old simply refreshing all the electrolytic capacitors can be worthwhile.Hope that helps.